Robert S. Staffanou

Review of the pH of hemostatic agents used in tissue displacement

Newer hemostatic agents such as the tetrahydrozolines and oxymetazolines have a more acceptable pH and should be kinder to tooth structure and soft tissue than the conventional solutions. Although additional study is needed, it would seem prudent to be cautious in using low pH hemostatic agents and avoid the exposure to sensitive intraoral tissues-particularly delicate tissues--or tooth preparation close to the dental pulp.

Bond strengths of high-palladium content alloys

Palladium-based alloys have had a significant import on the fabrication of ceramometal restorations. This article compares the bond strengths of four palladium-based alloys with that of a high-noble alloy. Tests were designed to closely represent clinical situations. Bond strengths of the palladium alloys compared favorably with the high-noble metals; palladium alloys containing up to 2% gold were the best.

Leakage of various types of luting agents

Freshly extracted molar teeth were prepared for complete cast gold crowns cemented with either zinc phosphate cement, polycarboxylate cement, glass ionomer cement, a resin luting agent, or a zinc oxide-eugenol temporary cement. The specimens were tested at 1-, 6-, and 12-month intervals with radioactive 45Ca. The specimens were sectioned, autoradiographs were made, and the marginal leakage was evaluated on a scale of 0 to 3. The results showed that zinc phosphate, polycarboxylate, and glass ionomer cements are equally suited for permanent cementation of restorations. The resin luting agent showed high initial leakage, indicating that it is not as desirable for permanent cementation purposes. The zinc oxide-eugenol cement showed increased leakage with time but is well suited for its indicated purpose, temporary cementation.

Strength properties of soldered joints for a gold-palladium alloy and a palladium alloy

Strength of a soldered palladium alloy, PGC (Engelhard Corp.), and a soldered medium gold alloy, PGX (Engelhard Corp.), was examined. The results obtained were as follows: Highest strength was observed with postsoldered specimens of PGC alloy. Microstructural examination of postsoldered specimens revealed nearly pore-free solder joints with PGC and PGX alloys, and fracture appeared at the solder-alloy interface with PGC and PGX alloys. Microstructural examination of presoldered and presoldered/thermocycled specimens revealed that presoldered specimens of PGC and PGX alloys exhibited intrasolder fracture; PGX solder joints had considerably less porosity, which may explain the equivalent bond strengths of all the soldered specimens and the yield point of the controls; PGC solder joints exhibited large quantities of pores, which may explain the lower strength; pores observed in PGC alloy may be the result of the high fusing temperature of the solder; and these results indicate a need to develop a new presolder for PGC. The best result was obtained with postsoldered specimens of the PGC alloy. However, for PGX alloy, either postsolder or presolder techniques can be used.

Evaluation of a new denture bath solution

Soft liners often lose their resiliency, perhaps as a result of oxidizing cleaning solutions and/or infiltration with Candida albicans. This project tested a new denture bath solution and its effects on liners treated with oxidizing solutions and with Candida inoculation. It appears that this denture bath solution has a definite softening effect on these liners.

Ceramo-metal bond strength of four palladium-rich alloys

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